1. Field of the Invention
This invention relates to a peroxide having a polymerizable double bond and a peroxide group in the molecule and more particularly to a novel peroxycarbonate which possesses excellent copolymerizability with non-conjugated ethylenically unsaturated monomers.
2. Description of the Prior Art
Heretofore, there have been known some peroxides having a polymerizable double bond. For example British Pat. No. 1,041,088 discloses that t-butyl peroxymethacrylate is copolymerized with methyl methacrylate whereby a copolymer having a peroxyester group is obtained and that the said copolymer is subjected to graft copolymerization.
Japanese Patent Publication No. SHO46-34100 discloses that di(t-butylperoxy) fumarate is copolymerized with styrene whereby there is obtained a copolymer having a peroxyester group and the said copolymer is subjected to graft copolymerization with methyl acrylate.
Japanese Patent Publication No. SH038-5972 discloses that t-butyl peroxycrotonate is copolymerized with vinyl chloride to obtain a copolymer having a peroxyester group and the thus obtained copolymer is mixed with a natural rubber latex at high temperature whereby blended polymers are obtained.
Japanese Patent Publication No. SH044-21721 discloses that resins which possess good extrusion properties and transparency are obtained by polymerization of ethylene using t-butyl peroxyvinylacetate.
As mentioned above, the peroxyesters having a polymerizable double bond are superior to the peroxyesters which do not contain a double bond in many points but the former peroxyesters also have some defects.
For example such compounds which self-polymerize easily such as butyl peroxymethacrylate as well as the acid chloride thereof, which are the starting materials therefor are not stable during storage and are inconvenient to handle.
Further, as the said peroxides are conjugated monomers, they are high in copolymerization reactivity with conjugated monomers having a Alfrey-Price value of 0.2 or above such as styrene, butadiene, methyl acrylate and methyl methacrylate but they are low in copolymerization reactivity with non-conjugated monomers having a Alfrey-Price value of lower than 0.2 such as vinyl acetate, vinyl chloride and di-allylphthalate [Refer to High Molecular Chemical Association: Copolymerization No. 1 Reaction Analysis (Baifukan) page 89]. As a result they are not suitable for copolymerization with the non-conjugated monomers.
Further, a compound which possesses high copolymerization reactivity such as di(t-butylperoxy)fumarate can not distribute the peroxyester groups in the polymer uniformly in a broad range of the concentration thereof.
Especially, when the concentration of the peroxyester groups is small, the peroxyester groups become present locally in the polymer with the result being that graft copolymers having good properties can not be obtained.
Furthermore, t-butylperoxycrotonate, because its peroxy group in the copolymer obtained by the copolymerization is a peroxyester of a secondary carboxylic acid, is active at low temperature and thus it is unsuitable for use as a free radical initiator at high temperature.